Council pitches rarely seem to be nice though let’s be honest. If the ECB cared they could buy up farm land, and rent it to smaller (not big clubs) clubs to make nice long term grounds
If the ECB had the money, which they don't, farmers are going to want to sell their land for development. Land gets sold at a price for which it will be used. A farmer who needs to sell their land are far more likely to do so to a housing developer for millions rather than donate the land to a sports club, as used to be the case, or for receational use.
You've only got to look at the number of housing developers adjacent to cricket amd sport clubs across former fatmland cropping up across the UK to see that's the case. The bygone days of farmers contributing land gratis are generally long gone.
Always, always, follow the money. Developers are often offering councils more money to develop on green space,as opposed to brownfield land as its cheaper to develop and doesn't need decontaminating. Same applies to farmers. Developers see rolling fields and views for executive homes, far more profit to be made there than apartmemts in towns...
Land is a valuable resource. There's not a public sports body that will be able to keep up with housing and commercial developers, alas.